A water vapor barrier is a material that prevents all, or mostly all, of water or water vapor from penetrating through the material. This is commonly known as having a water vapor transmission rate of approximately zero. A water vapor barrier may be desirable in situations to prevent moisture from moving or penetrating from one area to the next.
Flooring in residential or commercial buildings can be made with concrete. Concrete is a construction material composed of cement, as well as other cementitious materials such as fly ash and slag cement, aggregate, water, and chemical admixtures. Concrete solidifies and hardens after mixing with water and placement due to a chemical process known as hydration. The water reacts with the cement, which bonds the other components together, eventually creating a stone-like material.
Combining water with a cementitious material forms a cement paste by the process of hydration. The cement paste glues the aggregate together, fills voids within it, and allows it to flow more easily. The more water that is added to the cement paste, the more of an easier-flowing concrete is provided with a higher slump. This is extremely desirable when pouring concrete floors in building structures. The more slump, or easier-flowing the concrete is, the easier it is to pour the concrete floors. Thus, most concrete floors are poured with a cement paste with a relatively high amount of water.
Hydration involves many different reactions, often occurring at the same time. As the reactions proceed, the products of the cement hydration process gradually bond together the individual sand and gravel particles, and other components of the concrete, to form a solid mass. However, because of the large amount of water typically used when pouring concrete floors, some of the water is not used in the reaction process and eventually falls to the bottom of the concrete via gravity. In addition, because of the hydration process and presence of water, a water vapor is typically present around the outside of the concrete material. This extra water and water vapor below the concrete floor is then either absorbed into the subflooring material or trapped in an airspace between the subflooring material and the concrete. Both of these situations are undesirable as they can lead to mold, mildew and rotting of the subflooring materials. As a result, it is desirable to prevent this extra water and water vapor from entering the subflooring material or the airspace between the subflooring and the concrete flooring.
In addition, hydration and hardening of concrete during the first three days is critical. Properly curing concrete leads to increased strength and lower permeability, and avoids cracking where the surface dries out prematurely. The early strength of the concrete can be increased by keeping it damp for a longer period during the curing process. During this period concrete needs to be in conditions with a controlled temperature and humid atmosphere. Thus, there is a need to keep the water and water vapor used in the cement paste of concrete structures from flowing or absorbing out from the bottom of the concrete floor as it is being cured.
The instant invention is designed to provide a water vapor barrier for a concrete flooring system that addresses all the problems mentioned above.